Fuel supply system for an internal combustion engine

ABSTRACT

Fires in the fuel supply system for an internal combustion engine operating in a confined space are prevented by enclosing the carburetor of the engine in a vaportight housing and enveloping the fuel tube leading into the housing in an outer tubular casing. Air of combustion is drawn into the housing through a check valve during the intake stroke of the engine.

United States Patent [72] Inventors Franz-Josef Von Bomhard Sehweinlnrtam Main; Wolfgang Baier, Goehsheim, both of Germany [2]] Appl. No. 2,514

[22] Filed Jan. 13, 1970 [45] Patented Oct. 12, 1971 Fichtel & Sachs AGSchweinlurt, Germany [73] Assignee [32] Priority Jan. 18, 1969 [33)Germany [31] P19024403 [54] FUEL SUPPLY SYSTEM FOR AN INTERNALCOMBUSTION ENGINE 12 Claims, 7 Drawing Figs.

[52] US. Cl 123/136, 123/142, 123/195 C, 123/198 E, 26l/D1G. 55,123/D1G. 2 {51] Int. Cl ..F02m 17/30 [50] Field oiSearch 123/198, 198 E,195 A, 195 C, 142, 198 D, 141,142, 136, 139.16, 139 DP, 122 A, DIG, 2',261/D1G. 5S

[56] References Cited UNFTED STATES PATENTS 930,596 8/1909 Hanks [23/142X 1,283,302 10/1918 Reid 123/195 A 1,761,221 6/1930 Marx 123/142 PrimaryExaminer-A1 Lawrence Smith Attorneyl(e1man and Berman ABSTRACT: Fires inthe fuel supply system for an internal combustion engine operating in aconfined space are prevented by enclosing the carburetor 01 the enginein a vaportight housing and enveloping the fuel tube leading into thehousing in an outer tubular casingv Air of combustion is drawn into thehousing through a check valve during the intake stroke of the engine.

PATENIFDnmwmn 3.612.022

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ATENTFD BET 1 2 lGfl SHLEI 8 UF 6 AGE/Mfg FUEL SUPPLY SYSTEM FOR ANINTERNAL COMBUSTION ENGINE This invention relates to fuel supply systemsfor internal combustion engines, and particularly to a fuel supplysystem for an engine operating under conditions of high fire or explosion hazard.

The invention will be described hereinafter with reference to a smallauxiliary engine for a sailboat but other applications will readily cometo mind. It is convenient to equip a sailboat with a small inboard motorand a propeller to facilitate maneuvers in restricted harbor spaces andto provide propelling power when the weather is calm. The engine isnormally installed in a small compartment below deck, and boat fires arecaused relatively frequently when fuel, fuel vapors, or fuel mixtureaccidentally released from the fuel supply system are ignited on hotengine parts in the poorly ventilated engine compartment.

A primary object of the invention is the provision of a fuel supplysystem which permits an internal combustion engine to be used in aconfined space or under other conditions in which a relatively minoramount of fuel released from the fuel supply system may cause a fire oran explosion.

With this object and others in view, the invention provides a housingwhich encloses a cavity substantially sealed from the ambient atmosphereunder normal conditions. A check valve mounted on the housing admits airto the cavity when the pressure of the ambient air exceeds the fluidpressure in the cavity by a certain amount.

The cavity holds a carburetor or other mixing device for mixing theadmitted air with a liquid fuel. A supply conduit which passes throughthe housing communicates with the carburetor for supplying the same withthe fuel. A fuel mixture conduit passes through the housing andcommunicates with the carburetor for transferring the fuel mixture to anassociated internal combustion engine.

Other features, additional objects, and many of the attendant advantagesof this invention will readily be appreciated as the same becomes betterunderstood by reference to the following detailed description ofpreferred embodiments when considered in connection with the appendeddrawing in which:

FIG. I shows a fuel supply system of the invention and portions of anassociated internal combustion engine in sideelevational section;

FIGS. 2 and 3 illustrate the fuel supply system of FIG. I in respectivesections on the lines ll-Il and Ill-III;

FIG. 4 is a top plan view of the fuel system of FIG. 1;

FIG. 5 illustrates a part of the system of FIG. I in front elevationalsection;

FIG. 6 shows a modification of the fuel supply system of FIG. I in acorresponding view; and

FIG. 7 shows a further modification of the apparatus of FIG. 6 infragmentary side elevation.

Referring now to the drawing in detail, and initially to FIGS. I to 5,there is seen the single, air-cooled cylinder I7 and the piston 18 of aninternal combustion engine, not otherwise illustrated. The aperturedbottom of an approximately cupshaped portion 3 of a carburetor housingis directly attached to the intake port of the cylinder I7 by mountingscrews I7, the opening in the bottom of the portion 3 being sealed bythe discharge portion of a carburetor I2 mounted in the housing cavityand conventional in itself.

In the illustrated condition of the apparatus, the housing cavity issubstantially sealed by a cover portion 4 of the housing and an annulargasket 5 between the two housing portions which are held in engagementby a U-shaped wire strap 21. As is best seen in FIG. 4, the ends of thestrap are pivoted on the housing portion 3, and the center portion ofthe strap is received in a shallow groove in the outer wall of the coverportion 4.

A drain pan I1 is integral with the cover portion 4 and reaches into thehousing portion 3 to catch any liquid dripping from the carburetor 12.The pan 11 slopes downwardly toward sump I bounded by the cover portion4 in the lowermost part of the housing cavity. A partition 14 integralwith the cover portion 4 partly divides the housing cavity into twocompartments, the sump 10, pan 11, and carburetor l2 being located inthe compartment nearer the cylinder 17. A bottom wall of the othercompartment in the cover portion 4 is formed with a relatively largecircular aperture and provides a valve seat in the cavity for a checkvalve I whose valve disc is guided toward and away from the seat by astem movably received in a spider in the aperture. The valve I is biasedtoward the closed position by its own weight and by a helicalcompression spring 22 interposed between the valve stem and the spider.An annular groove I3 in the bottom wall is open toward the housingcavity and slopes slightly toward horizontal openings IS in thepartition 14. The partition partly bounds the sump I0, and the groove 13thus communicates through the openings 15 with the sump for gravity flowof liquid from the groove into the sump.

Fuel is supplied to the carburetor 12 through a fuel line best seen inFIG. 2. A nipple 9 is threadedly mounted in the housing portion 3. Anouter pipe 8 is sealed to the nipple 9 to form therewith a protectivecasing for a fuel tube 7 approximately coaxially mounted in the pipe 8and the nipple 9. The effective flow section of the annular gap betweenthe nipple 9 and the tube 7 is only a small fraction of the flow sectionof the valve I when the latter is opened by the pressure of the ambientair during the intake stroke of the piston Ill.

The throttle in the carburetor 12 is controlled in a conventional mannerby a Bowden wire which enters the housing cavity through an opening inthe housing portion 3 and a seal assembly 6. The latter mainly consistsof a resilient plastic cap I9 which grips the outer sleeve 23 of thecarburetor operating wire 20 and envelops the screw 24 which permits theeffective length of the wire to be adjusted in a known manner.

Access to the carburetor I2 may be had by swinging the strap 21 from theillustrated position and thereafter removing the cover portion 4. Thescrew on the carburetor which con trols the idling speed is accessiblethrough an opening in the fixed housing portion 3 normally sealed by athreaded plug or cover member I6 as is seen in FIG. 5. Additionalopenings and sealing plugs may be provided for routine adjustments.

The fuel tube 7 is connected with a nonillustrated fuel tank in awell-ventilated portion of the boat and is covered by the pipe 8 overits entire length. The annular gap between the tube 7 and the pipe 8 maybe open to the atmosphere at a point remote from the housing 3, 4without significantly affecting the operation of the valve I because ofthe small effective flow section of the gap. If the tank is locatedabove the illustrated devices, and fuel flows by gravity to thecarburetor l2, fuel leaking from the tube 7 runs into the housing cavityalong the tube, drips from the nipple 9 into the pan II, and isultimately collected in the sump 10. Fuel droplets sprayed into the housing cavity from the air intake of the carburetor I2 are directed largelytoward the partition I4, and flow along the partition into the sump. Anydroplets which find their way into the valve compartment in the coverportion 4 flow into the groove 13 and also find their way into the sump.

The collected fuel may be removed from time to time by releasing thecover portion 4 from the fixed housing portion 3, and pouring the liquidback into the fuel tank. The carburetor controls, the fuel line, and theconduit transferring fuel mixture from the carburetor 12 to the cylinder17 need not be disturbed during this operation.

The fuel supply system illustrated in FIG. 6 differs from that describedabove by the configuration of the housing cover 4' and by elementsassociated therewith. The cover 4' is a flat dish of approximatelycylindrical shape about a horizontal axis. A pocket in the sidewall ofthe dish provides the sump 10, and a drain pan II integral with thecover 4' extends under the carburetor I2 and the fuel supply nipple 9 inthe fixed housing portion 3, as described above.

The upright radial wall of the cover 4' has a relatively large openingin its top portion upwardly remote from the sump 10. The opening isnormally closed by a check valve 2 mainly consisting of a resilientvalve flap 26 and a valve seat 25. During the intake stroke of thepiston 18, the pressure of the ambient air is sufficient to deflect theflap 26 against its own resilient force inwardly of the housing cavityaway from the seat 25, as is shown in FIG. 6. When the pressuredifferential across the valve 2 is insufficient to overcome therestraint of the flap 26, which is attached to the cover 4', the flapengages the seat 25 and seals the housing cavity from the ambientatmosphere. No significant amounts of fuel or fuel vapors can escapefrom the housing 3, 4'.

When it is desired to empty the sump 10, a wire strap 21' joumaled in aboss of the cover 4 is swung out of engagement of its nonillustrated,hook-shaped ends with projections on the fixed housing portion 3, andthe fuel is poured back from the sump into the nonillustrated fuel tank.

If fuel tends to collect relatively fast in the sump 10 by condensationor otherwise, it may be inconvenient to release the cover portions 4, 4'from the fixed housing portion 3 for recovering the fuel, and the sumpmay be emptied by means of a suction pump which is operatedintermittently by hand. An automatic suction arrangement which preventsthe accumulation of fuel in the sump, and thereby further improves thesafety of the apparatus of FIG. 6 is shown in FIG. 7 from which manyelements of FIG. 6, not themselves relevant to the suction arrangement,have been omitted.

The cover 4" seen in FIG. 7 differs from the aforedescribed cover 4'solely by a narrow radial bore in the lowermost wall of the sump l0. Asuction tube 30 leads from the bore to the fuel mixture conduit 31 whichconnects the carburetor, not itself seen in FIG. 7, to the intake portof the cylinder 17, and more specifically to a ring 32 clamped betweenthe housing portion 3 and the cylinder 17 by mounting screws l7 whichalso attach the housing portion 3 to the cylinder.

The axial opening of the ring 32 converges and diverges in the manner ofa venturi, and a radial bore leading into the narrow throat of the ringis connected to the suction tube 30. During each intake stroke of thepiston, fuel is drawn from the sump 10 into the ring 32. It is atomizedand enriches the fuel mixture transferred from the carburetor to theengine.

It should be understood, of course, that the foregoing disclosurerelates only to preferred embodiments of the invention, and that it isintended to cover all modifications and variations of the examples ofthe invention herein chosen for the purpose of the disclosure which donot constitute departures from the spirit and scope of the invention asset forth in the appended claims.

1. A fuel supply system for an internal combustion engine comprising, incombination:

a. a housing enclosing a cavity normally substantially sealed from theambient atmosphere;

b. a check valve mounted on said housing for admitting air to saidcavity when the pressure of said air exceeds the fluid pressure in saidcavity by a predetermined amount;

c. mixing means in said cavity for mixing the admitted air with a liquidfuel;

d. a supply conduit passing through said housing and communicating withsaid mixing means for supplying fuel to said mixing means;

e. a fuel mixture conduit passing through said housing and communicatingwith said mixing means for transferring the mixture of air and fuel toan associated internal combustion engine; and

f. an elongated tubular casing sealed to said housing and spacedlyenclosing a portion of said supply conduit outside said cavity.

2. A system as set forth in claim 1, wherein said housing includes twohousing portions and releasable sealing means for nonnally holding saidportions in sealing engagement about said cavity, the system furthercomprising mounting means for mounting one of said portions in fixedspatial relationship to said engine, at least one of said conduitsextending in said one portion.

3. A system as set forth in claim 2, further comprising control meansfor controlling the operation of said mixing means, said control meansincluding a control member, said one portion being formed with anopening, and said control member movabiy passing through said opening insealing relationship with said one portion and being operativelyconnected to said mixing means.

4. A system as set forth in claim 2, wherein said one portion defines anaperture normally covered by the other portion of said housing, saidaperture being dimensioned and located to give access to said mixingmeans.

5. A system as set forth in claim 2, wherein said one portion is formedwith an aperture dimensioned and located to give access to said mixingmeans, the system further comprising a cover member releasably receivedin said aperture and normally sealing the same.

6. A system as set forth in claim 2, wherein the other portion of saidhousing is formed with an aperture, said check valve being mounted onsaid other portion and normally sealing the aperture of the same.

7. A system as set forth in claim 1, wherein said casing and said supplyconduit define therebetween a gap having an effective flow section muchsmaller than the effective flow section of said check valve in the opencondition of the latter.

8. A fuel supply system for an internal combustion engine comprising, incombination:

a. a housing enclosing a cavity normally substantially sealed from theambient atmosphere,

l. said housing including two housing portions and releasable sealingmeans for normally holding said por tions in sealing engagement aboutsaid cavity;

b. mounting means for mounting one of said portions in a predeterminedspatial position, a part of the other portion of said housing bounding asump in the lowermost portion of said cavity in said predeterminedposition of said one portion:

c. a check valve mounted on said housing for admitting air to saidcavity when the pressure of said air exceeds the fluid pressure in saidcavity by a predetermined amount;

d. mixing means in said cavity for mixing the admitted air with a liquidfuel;

e. a drain pan located under said mixing means in said cavity andsloping toward said sump in said position of said one portion;

. a supply conduit passing through said housing and communicating withsaid mixing means for supplying fuel to said mixing means; and

g. a fuel mixture conduit passing through said housing and communicatingwith said mixing means for transferring the mixture of air and fuel toan associated internal combustion engine.

9. A system as set forth in claim 8, wherein said other portion of saidhousing is formed with an aperture and a groove spacedly adjacent saidaperture and open toward said cavity, said check valve being mounted onsaid other portion and normally sealing said aperture, said groovecommunicating with said sump.

10. A system as set forth in claim 9, further comprising a partition insaid cavity interposed between said aperture and said mixing means andpartly dividing said cavity, said partition being formed with an openingtherethrough communicating with said groove and with said sump for flowof liquid from said groove to said sump in said position of said oneportion.

ll. A fuel supply system for an internal combustion engine comprising,in combination:

a. a housing enclosing a cavity normally substantially sealed from theambient atmosphere;

1. said housing including two housing portions and releasable sealingmeans for normally holding said portions in sealing engagement aboutsaid cavity;

b. mounting means for mounting one of said portions in a predeterminedspatial position, a part of the other portion of said housing bounding asump in the lowermost portion 6 of said cavity in said predeterminedposition of said one municating with said mixing means for supplyingfuel to portion; said mixing means; and c. a check valve mounted on saidhousing for admitting air 3. a fuel mixture conduit passing through saidhousing and to said cavity when the pressure of said air exceeds thecommunicating with said mixing means for transferring fluid pressure insaid cavity by a predetermined amount; 5 the mixture of air and fuel toan associated internal comd. mixing means in said cavity for mixing theadmitted air bllslion g with a liquid fuel; 12. A system as set forth inclaim ll, wherein said suction Suction means communicating with saidsump f means include a suction conduit connecting said sump withwithdrawing li id f m h same; said fuel mixture conduit.

f. a supply conduit passing through said housing and com-

1. A fuel supply system for an internal combustion engine comprising, incombination: a. a housing enclosing a cavity normally substantiallysealed from the ambient atmosphere; b. a check valve mounted on saidhousing for admitting air to said cavity when the pressure of said airexceeds the fluid pressure in said cavity by a predetermined amount; c.mixing means in said cavity for mixing the admitted air with a liquidfuel; d. a supply conduit passing through said housing and communicatingwith said mixing means for supplying fuel to said mixing means; e. afuel mixture conduit passing through said housing and communicating withsaid mixing means for transferring the mixture of air and fuel to anassociated internal combustion engine; and f. an elongated tubularcasing sealed to said housing and spacedly enclosing a portion of saidsupply conduit outside said cavity.
 2. A system as set forth in claim 1,wherein said housing includes two housing portions and releasablesealing means for normally holding said portions in sealing engagementabout said cavity, the system further comprising mounting means formounting one of said portions in fixed spatial relationship to saidengine, at least one of said conduits extending in said one portion. 3.A system as set forth in claim 2, further comprising control means forcontrolling the operation of said mixing means, said control meansincluding a control member, said one portion being formed with anopening, and said control member movably passing through said opening insealing relationship with said one portion and being operativelyconnected to said mixing means.
 4. A system as set forth in claim 2,wherein said one portion defines an aperture normally covered by theother portion of said housing, said aperture being dimensioned andlocated to give access to said mixing means.
 5. A system as set forth inclaim 2, wherein said one portion is formed with an aperture dimensionedand located to give access to said mixing means, the system furthercomprising a cover member releasably received in said aperture andnormally sealing the same.
 6. A system as set forth in claim 2, whereinthe other portion of said housing is formed with an aperture, said checkvalve being mounted on said other portion and normally sealing theaperture of the same.
 7. A system as set forth in claim 1, wherein saidcasing and said supply conduit define therebetween a gap having aneffective flow section much smaller than the effective flow section ofsaid check valve in the open condition of the latter.
 8. A fuel supplysystem for an internal combustion engine comprising, in combination: a.a housing enclosing a cavity normally substantially sealed from theambient atmosphere,
 9. A system as set forth in claim 8, wherein saidother portion of said housing is formed with an aperture and a groovespacedly adjacent said aperture and open toward said cavity, said checkvalve being mounted on said other portion and normally sealing saidaperture, said groove communicating with said sump.
 10. A system as setforth in claim 9, further comprising a partition in said cavityinterposed between said aperture and said mixing means and partlydividing said cavity, said partition being formed with an openingtherethrough communicating with said groove and with said sump for flowof liquid from said groove to said sump in said position of said oneportion.
 11. A fuel supply system for an internal combustion enginecomprising, in combination: a. a housing enclosing a cavity normallysubstantially sealed from the ambient atmosphere;
 12. A system as setforth in claim 11, wherein said suction means include a suction conduitconnecting said sump with said fuel mixture conduit.